Extra copies of the normal alpha synuclein (SNCA)
gene cause an inherited form of Parkinson disease, according to a new report
in the October 31 issue of Science. Researchers from
the National Institute of Health and several US medical centers studied a
large family in which many relatives developed the disease, and linked the
disease to the presence of two extra copies of SNCA.

Mutations in the SNCA gene had been implicated
in Parkinson disease in other families, but the new data suggest that the
disorder can also result when extra copies of the normal version of the gene
produce too much synuclein protein. The excess protein may form aggregates
that interfere with dopamine-releasing neurons in the brain.